Date issued

Dec 11, 2017 - 4:55 PM

Valid until

Dec 12, 2017 - 4:00 PM

Prepared by

brian webster

A strong temperature inversion results in above freezing temperatures in the alpine. Ice climbers be cautious, now is a good time to avoid being under south facing slopes in the afternoon.

Regular season
Monday - December 11, 2017
Alpine

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Treeline

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Below Treeline

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Tuesday - December 12, 2017
Alpine

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Treeline

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Below Treeline

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Wednesday - December 13, 2017
Alpine

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Treeline

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Below Treeline

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Avalanche Problem 1: Persistent Slabs

What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?

Some uncertainty for triggering various mid-pack layers remain, but we have come through a warm period and a lot of skier testing produced no activity over the past five days. These slabs still deserve respect in steep and shallow areas.

Travel and Terrain Advice
  • Be aware of thin areas that may propogate to deeper instabilites.

Avalanche Summary

During the last few days with inverted temperatures yielding above freezing conditions treeline and above, only a few very small loose wet avalanches in the alpine were observed. These were in steep rocky terrain that was in the sun, and sheltered from the wind. Where observed, these did not triggered any deeper weaknesses.

Snowpack Summary

Small surface hoar in sheltered locations at tree-line. Sun crusts, surface faceting and wind effect on various aspects in the alpine. 15-40 cm of snow lies over the Nov 27th and Nov 23rd crusts. Both of these now overlie the Halloween crust/facet layer that sits 30-50cm above the ground.

Weather Forecast

The high pressure ridge will dominate the region until at least Thursday. Temperatures will remain inverted with above freezing temperatures in the alpine and cooler temperatures at the valley bottoms. A weak upper low crossing the region on Tuesday will cause some high level cloud cover and some stronger winds but no precipitation is expected. 

Danger Ratings Explained

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

3 - Considerable

Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

Natural avalanches possible; human-triggered avalanches likely.

Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

4 - High

Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

Natural avalanches likely; human-triggered avalanches very likely.

Large avalanches in many areas; or very large avalanches in specific areas.

5 - Extreme

Avoid all avalanche terrain.

Natural and human-triggered avalanches certain.

Large to very large avalanches in many areas.

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